The problems don't always lie in the bottom end tuning --- that part is dead easy. Not all of these engines run well, as they are highly variable in quality. They are essentially the same engine as the GMS .47 (identical?) except that Tower doesn't offer a front NV (like it should). The GMS quality level is slightly higher, but not great. The Tower varient is built down to the last half of the last penny & they generally suck.

Proper tuning helps, but doesn't fix junk.